Fuel injection pump

ABSTRACT

The present invention relates to a fuel injection pump for internal combustion engines, having a pump housing, in which a feed device is accommodated, whose operation is controlled with the aid of a control unit that is accommodated in a control-unit housing mounted to the pump housing.  
     In order to ensure that the control-unit housing is sufficiently cooled, a cavity, into which a fuel inlet empties and at which a connecting line leading to the feed device originates, is formed between the upper side of the pump housing and the lower side of the control-unit housing;  
     a filler piece having an inlet tulip ( 18 ) being situated in the cavity, the delivered fuel being directed from the cavity, through the inlet tulip and the connecting line, to the feed device.

BACKGROUND INFORMATION

[0001] The present invention relates to a fuel injection pump forinternal combustion engines, having a pump housing, in which a feeddevice is accommodated, whose operation is controlled with the aid of acontrol unit that is accommodated in a control-unit housing mounted tothe pump housing.

[0002] Such an injection pump is known from DE OS 34 03 073 A1. In theknown injection pump, the fuel to be delivered is directed through thecontrol-unit housing for cooling purposes. Practical use has shown theheating of electrical components in the control-unit housing to beproblematic.

[0003] The object of the present invention is to ensure sufficientcooling of the control-unit housing, without fuel flowing aroundelectronic components contained in the interior of the control-unithousing.

[0004] This object is achieved by a fuel injection pump for internalcombustion engines, having a pump housing, in which a feed device isaccommodated, whose operation is controlled with the aid of a controlunit that is accommodated in a control-unit housing mounted to the pumphousing; in that

[0005] a cavity, into which a fuel inlet empties and from which aconnecting line to the feed device originates, is formed between theupper side of the pump housing and the lower side of the control-unithousing; and in that

[0006] a filler piece having at least one diverter channel is situatedin the cavity, the delivered fuel being directed from the fuel inlet tothe lower side of the control-unit housing, via the diverter channel.

SUMMARY OF THE INVENTION

[0007] In this manner, the lower side of the control-unit housing iscontinuously wetted with fuel during operation, which results in aconsiderably improved cooling effect.

[0008] A particular embodiment of the present invention is characterizedin that a mask is formed on the filler piece, the mask surrounding thefuel inlet in the pump housing when the filler piece is installed. Themask ensures that the fuel from the fuel inlet reaches the diverterchannel. The mask prevents the fuel from taking a direct,short-circuit-flow path from the fuel inlet to the connecting line.

[0009] Another particular embodiment of the present invention ischaracterized in that the diverter channel starts out from a tab, whichis formed on the filler piece and, in the installed state of the fillerpiece, is accommodated in a pocket that is taken out in the pumphousing, in the region of the fuel inlet. This first of all improves theeffect of the mask. Secondly, the tabs received in the pockets are usedto hold the filler piece in position, in the installed state.

[0010] Another particular embodiment of the present invention ischaracterized in that an inlet tulip is formed in the upper surface ofthe filler piece facing the control-unit housing, the inlet tulip beingconnected to the connecting line in the pump housing, when the fillerpiece is installed. The inlet tulip acts as a funnel and ensures thatthe fuel is sucked in from above, and that the formation of air bubblesis prevented. Air still present in the cavity is dispersed in very smallunits in the aspirated fuel, using the filler piece of the presentinvention.

[0011] A further, particular embodiment of the present invention ischaracterized in that all of the fuel channels provided in the fillerpiece are designed to have a low resistance to flow. This ensures thatthe pressure drop across the filler piece is kept as low as possible.

[0012] Another particular embodiment of the present invention ischaracterized in that the inlet of the connecting line in the pumphousing is funnel-shaped. This keeps the pressure drop low.

[0013] Another particular embodiment of the present invention ischaracterized in that two diverter channels are provided on oppositesides of the filler piece. This has the advantage of the filler piecebeing able to be attached on two opposite sides of the pump housing.

[0014] A further particular embodiment of the present invention ischaracterized in that, a plurality of chambers open from below areformed in the filler-piece surface that faces the pump housing in theinstalled state of the filler piece. The subdivision of the lower sideof the filler piece into several chambers reduces the volume of airpossibly trapped in the cavity to a safe value.

[0015] Additional advantages, features, and details of the presentinvention result from the subsequent description, in which an exemplaryembodiment of the present invention is explained in detail withreference to the drawing. In this context, the features mentioned in theclaims and the Specification may each be essential to the presentinvention, either alone or in arbitrary combination.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The figures in the drawing show:

[0017]FIG. 1 a perspective view of a filler piece according to thepresent invention;

[0018]FIG. 2 a rear view of the filler piece from FIG. 1; and

[0019]FIG. 3 a bottom view of the filler piece from FIG. 1.

[0020] The filler piece shown in perspective in FIG. 1 is accommodatedin a cavity, which is formed between the upper side of the pump housingand the lower side of the control-unit housing of an injection pumpaccording to the present invention. Emptying into the cavity is a fuelinlet, through which fuel from a fuel tank reaches the cavity. The fuelmay either be transported in the cavity with the aid of a presupplypump, or drawn in by the feed pump of the injection pump alone. Aconnecting line leads from the cavity to the feed device of theinjection pump. The opening for the connecting line is situated in thecavity, above the opening for the fuel inlet. This causes the cavity toconstantly be filled with fuel to a certain level. In addition, acertain amount of air in the cavity cannot be avoided during operation.The cavity is delimited from below by the pump housing of the injectionpump. The cavity is delimited-from above by the lower side of acontrol-unit housing. The control-unit housing is used to accommodateelectronic components, which heat up during operation.

[0021] In the installed state, the filler piece represented in FIG. 1 isaccommodated in the cavity in such a manner, that its upper side 1 isturned towards the lower side of the control-unit housing. As a rule,upper side 1 of the filler piece is horizontally positioned, in theinstalled state. Eight planar side faces 2 through 9 extend in anessentially vertical direction, from upper side 1 of the filler piece. Adiverter channel 11 is removed from planar side face 9 of the fillerpiece. A diverter channel 12 is removed from planar side face 5 of thefiller piece. Diverter channel 11 extends from a tab 13, which is usedto position the filler piece, to upper side 1 of the filler piece.Diverter channel 12 likewise extends from a tab 14 to upper side 1 ofthe filler piece. A mask 15, which, in the installed state, surroundsthe intake port of the fuel inlet in the cavity, is formed on tab 13. Acorresponding mask is formed on tab 14. The fuel entering into thecavity is directed through diverter channels 11 and 12, to upper side 1of the filler piece. In this manner, it is ensured that the lower sideof the control-unit housing is wetted with fuel. The positioning of thediverter channel is selected so that a certain mass flow rate of fuelstrikes the control-unit surface, over which the electronic modulehaving the greatest heat loss is situated. The heat is dissipated, usingcorrection.

[0022] An inlet tulip 18 is formed in the center of upper side 1 of thefiller piece. Inlet tulip 18 is connected to fuel outlet 20 viaconnecting tube 19. In the installed state of the filler piece, fueloutlet 20 is situated near the inlet of the connecting line leading tothe feed device of the injection pump. Fuel outlet 20 is situated on abeveled surface 21 of the filler piece. The positioning of the inlettulip on the top allows the air accumulated on top to be continuouslyremoved and thus ensures that the lower side of the control-unit housingremains wetted with fuel. The funnel-shaped design of the inlet tulipalso produces a lower resistance to the flow of fuel.

[0023] Two guide pins 25 and 26, which are slotted on the end, projectoutwards from the lower side of the filler piece. In the installedstate, guide pins 25 and 26 are used to lock the filler piece inposition in the cavity.

[0024] In the bottom view represented in FIG. 3, one can see that thefiller piece is subdivided into several block-shaped chambers 30, 31,which are open from below. Chambers 30, 31 are formed by verticalpartitions, which are positioned perpendicularly to each other.

[0025] The filler piece of the present invention ensures that the fuelis directed on, between the pump housing and the control-unit housing.This minimizes the pressure drop. In addition, the filler-piece designaccording to the present invention ensures that air is continuouslyexhausted from the cavity.

[0026] In the installed state of the filler piece, fuel flows from thefuel inlet into the space formed between the lower side of thecontrol-unit housing and the upper side of the filler piece. The coolingaction of the fuel takes place in this space. The fuel travels from thespace, through inlet tulip 18 and connecting tube 19, to the connectingline (not shown) leading to the feed device of the injection pump. Thedesign of the filler piece of the present invention to allow the fuel tobe drawn off through the highest point, using an inlet tulip, or to beat least drawn off through the inlet tulip, or to only drain off throughthe inlet tulip, ensures that the cavity is at least filled up to upperside 1 of the filler piece.

What is claimed is:
 1. A fuel injection pump for internal combustionengines, having a pump housing, in which a feed device is accommodated,whose operation is controlled with the aid of a control unit that isaccommodated in a control-unit housing mounted to the pump housing,wherein a cavity, into which a fuel inlet empties and from which aconnecting line leading to the feed device originates, is formed betweenthe upper side of the pump housing and the lower side of thecontrol-unit housing; and a filler piece having at least one diverterchannel (11) is situated in the cavity, the delivered fuel beingdirected from the fuel inlet, through the diverter channel, to the lowerside of the control-unit housing.
 2. The fuel injection pump as recitedin claim 1, wherein a mask 15, which surrounds the fuel inlet in thepump housing when the filler piece is installed, is formed on the fillerpiece.
 3. The fuel-injection pump as recited in one of the precedingclaims, wherein the diverter channel (11) originates at a tab (13),which is formed on the filler piece and, in the installed state of thefiller piece, is accommodated in a pocket that is taken out in the pumphousing, in the region of the fuel inlet.
 4. The fuel injection pump asrecited in one of the preceding claims, wherein an inlet tulip (18) isformed in the upper surface (1) of the filler piece facing thecontrol-unit housing, the inlet tulip being connected to the connectingline in the pump housing, when the filler piece is installed.
 5. Thefuel-injection pump as recited in one of the preceding claims, whereinall of the fuel channels (11, 12, 19) provided in the filler piece aredesigned to have a low resistance to flow.
 6. The fuel-injection pump asrecited in one of the preceding claims, wherein the inlet of theconnecting line in the pump housing is formed in the shape of a funnel.7. The fuel-injection pump as recited in one of the preceding claims,wherein two diverter channels (11, 12) are provided on opposite sides ofthe filler piece.
 8. The fuel-injection pump as recited in one of thepreceding claims, wherein, in the installed state of the filler piece, aplurality of chambers (30, 31) open in the downward direction are formedin the filler-piece surface that faces the pump housing.